ELECTROCHEMISTRY OF IRIDIUM TRIS-(PHENANTHROLINE) AND BISESQUIS-(PHENANTHROLINE) COMPLEXES

Cyclic voltammetry data have been obtained for the tris- and bisesquis(1,10-phenanthroline) (phen) complexes of iridium(III) in acetonitrile. A reaction mechanism is proposed on the basis of the analysis of electrochemical and luminescence data. For the bisesqui- and tris(phen) complexes the mechanisms are similar to the corresponding 2,2′-bipyridine (bpy) Ir(III) complexes except that an insoluble deposit forms after three electrons have been transferred. Similar behavior has been observed for the reduction of [Ru(bpy)3]2+, however, comparison of the reverse (oxidation) scan for the first reduction wave of the tris Ir(III) and Ru(II) complexes indicates distinctly different behavior. These data are interpreted as resulting from the multiring delocalized redox orbital of the Ru(II) complex and the single ring delocalized redox orbital of the Ir(III) complex. © 1979 American Chemical Society.